Electroplating copper on aluminum



Patented Jan. 31, 1950 1 hireo STATES PATENT OFFICE. ELECTItOPLATINZ ZZ Zi ER N ALIlMIN Lucio 1F. Mondolfo, Sea Cliff, N. Y., assignor to Reynolds Metals Company, Richmond, Va., acorporation of Delaware i No'Drawing. Application December 18, 1946,

Serial No. 717,083, 5 Claims. (01.204-42) anodized at the same time. After an. appropriate interval to minutes being usually This invention relates to the electroplating of ticle in the center is removed aluminum and'has for its object the provision of an improved method of electroplating copper on sufficient), the ar aluminum M n ion pr vides an an d zin and one of the articles at the sides; for example, the one at the right side is movedto the center and electroplating operation carried out with the 5 same sol ti n and advanta eously in the same and made the cathode. A new article to be plated vessel. One of the important features of my inis placed at the rig vention is the use of an electrolyte including a moved to the center strong acid b means of which I may form an for th same interval of tim anodic coa in on he al minum an a deposit 10 time the article in the center is again removed, f p r v r he anodlc coating in the same the article at the left side is placedin the center, solution merely y using the aluminum s an and anew article is placed on .theleft side. This node w le m n h o ng and then as operation is repeated at the end of each time incathode when depositing th copp r terval, moving the articles alternatingly from the 'lneccorda-nce with my invention; the t t to 15 right and left to the center. This way the operabe plated W copper with prehmi' tion is continuous and full advantage is taken of y Clea-11mg: and advantageously Without the the vessel and the current because articles are becareful and expensive preparation heretofore remg anodized and plated a the Same time quiredjs immersed in a water solution of copper If the articles to be plated are relatively flat d Sulfuric acid for anodizing and plat and are to be plated only on one side, the same sulfate an In practlcmg i g i my a arrangement can be used by reversing the cong a 3 55 if o g as nections, so that the article in the center 'is the ca 0 e e a at t e as e anode and the articles at the sides are the cathwhile forming the anodic coating. Direct curodes This way taking advantage of rr w rent is applied to the electrodes in the usual way t hrowlng power of the solution, only the side and the anodizing is carried on until the desired which faces cathode will be plated, the other anodic film or coating is formed on the aluminum articlewhich requires. approximately 10 to slde tecewmg no n n i i t minutes. The current flow is then reversed mak- 'ee e l for Successwe hi i if requred' ing the aluminum article the cathode and the cop- 3o one f 99m features y nt? per plate the anode. In this phase of the operaa I can fm t y desu'ed h n i tion, copper is deposited over the anodic coating P when h Q F plated t m-m on the aluminum article. e? F h l' i nt. i mk i f In another adaptation of my invention, I mm purpose for which it is intended, the article is taken out of the bath and rinsed, and the platmerse at least two aluminum articles in the solution and connect them as electrodes or poles to a mg is COmmFtEd' adherence of Copper source of alternating current, preferably of low to T alummum 15 very good" The plated frequency In this Step of the Operation I f terlal can be formed, buffed or heated up to the an anodic coating without using direct current. melting point of the aluminum Without any P After the desired anodic coating has formed on 40 mg of the copperthe articles, the alternating current is switched In referring herein "aluminum? I n end to include pure aluminum, ordinary commercial aluoff and the aluminum articles are preferably connected in parallel. A direct current is then conminum with its usual imp and um n m nected to the articles as cathodes and a copper alloys- The main advantages of the method are;

body or plate is used as anode. The copper plating is carried out as described above. 1. Very good adhesion of the copper to the Another variation of my invention which is m mparticularly suited for continuous operations is 2. No expensive or careful preparation of e as follows: In a vessel containing the solution surface is required before the article is immersed in the bath. If the article is fairly clean, no pre three articles are suspended in such a way that one is in the middle of the other two. The article treatment at all is required; if it is very dirty in the center is made the cathode and the articles or very greasy, it is better to remove the dirt or at the sides are connected in parallel as anodes. greaseto minimize undue contamination or the When direct current is passed, the article in the electrolyte, but it is not absolutely necessary.

center is plated, the articles at the sides being 3. The article is handled only when it is immersed in the bath and when it is taken out. No careful handling is required.

4. Only one solution is used so that only one tank is required.

The solution to be used for surface and for plating is cheap sity, me, temperature and voltage are not c11tical. Relatively Wide variations can be tolerated. In the following example a sheet of 38 alloy of 0.010 gage was plated in the H temper:

Direct Current Anodizing Plating Volts 25 Volts, v i. 6 Amp/sq ft 12 Amp./sq.ft 15 Time n1i11utes 15 Time "minutes" 15 Temperature 100 Temperature F iOO The solution used contained approximately:

20% Cu sulfate 2% H2804 After plating the sample was annealed at 650- 750 F. for minutes, pickled cracking taking place on the plating.

I claim:

1. The method of electroplating copper on aluminum which comprises immersing at least two aluminum articles in a Water solution of sulfuric acid and copper sulfate, applying an alternating current-to the two articles as electrodes and forming an anodic coating thereon, discontinuing the 5 minum articles which comprises placing at least three fiat articles in an aqueous solution of sul furic acid and copper sulfate, in the center and the other anodizing the opposite faces of the anode.

LUCIO F. MONDOLFO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES Chemical Abstracts 29 (1935), 24159. 

1. A METHOD OF ELECTROPLIATING COPPER ON ALUMINUM WHICH COMPRISES IMMERSING AT LEAST TWOALUMINUM ARTICLES IN A WATER SOLUTION OF SULFURIC ACID AND COPPER SULFATE, APPLYING AN ALTERNATING CURRENT TO THE TWO ARTICLES AS ELECTRODES AND FORMING AN ANODIC COATING THEREON, DISCONTINUING THE USE OF ALTERNATING CURRENT, CONNECTING THE ARTICLES IN PARALLEL AS CATHODES AND A BODY OF COPPER AS ANODE TO A SOURCE OF DIRECT CURRENT AND DEPOSITING COPPER ON THE ARTICLES. 